1. Field of the Invention
The present invention generally relates to methods and systems for mail transmission. Specifically, the invention provides a mechanism especially appropriate for the transfer of a great number of e-mails addressed to multiple recipients.
2. Description of the Related Art
As the use of e-mail has spread explosively, senders, including a variety of different companies, have come to rely on it for the dissemination of topical product and service information for clients. For example, manufacturers use e-mail to advertise new products, while banks and stock brokerages employ it for the distribution of stock exchange and stock price information. In general, information distribution services are on the increase, and even today, there are some companies that distribute relevant information to several hundreds of thousands of clients.
As is well known, when preparing to dispatch an e-mail, a sender creates e-mail data by entering a mailing address of a recipient, a subject and a text, and then transmits this data to a mail server the sender uses. Thereafter, based on the mailing address, the mail server transmits the e-mail data, via the Internet, to the mail server that the recipient uses. Then, by accessing the mail server, the recipient can retrieve and read the e-mail transmitted by the sender. Or, if the recipient subscribes to an e-mail service provided via a mobile phone terminal, in order to retrieve the e-mail, he or she can not only access the mail server whenever it is convenient, but also can wait until a notification is received from the mail server.
A communication protocol called SMTP (Simple Mail Transfer Protocol), shown in FIG. 1, is employed to transmit e-mail data from a mail server that a sender uses to a mail server that a recipient uses. Predetermined procedures, such as “request for connection”, “SMTP standby OK”, “sender address”, “acknowledge sender address”, “sender mailing address” and “acknowledge sender mailing address”, are performed between the transmission side (the mail server used by the sender) and the reception side (the mail server used by the recipient), and then, “mail text” data is transferred.
The mail transfer between the mail servers using SMTP is also performed in the above described information distribution service for a large number of recipients using e-mails.
However, when this conventional technique is used, the following problems are encountered.
As is shown in FIG. 1, in the SMTP, many procedures must be performed before and after the e-mail text is transferred. In addition, during the e-mail transfer process, steps in consonance with the number of e-mails to be transferred are required among the mail servers of the transmission sides and reception sides. Since there is a hardware restriction on this process, the number of processes that can be performed in parallel is limited.
While no critical problem is encountered so long as the volume of the e-mail transmitted is small, transmitting a lot of e-mails, for example, several hundred thousand e-mails, takes a great deal of time. For instance, currently, a conventional mail server that can transfer ten e-mails per second by the current SMTP requires at least five hours to complete the transfer of two hundred thousand e-mails.
Further, in accordance with SMTP, e-mail is not directly transmitted by the mail server of the sender to the mail server of the recipient, but instead is relayed via (multiple) SMTP servers on the Internet. That is, e-mail data from the sender is sequentially transferred from one server to another until finally the mail server of the recipient is reached. During this transmission processing, the procedures shown in FIG. 1 are performed between two contiguous servers using SMTP. Therefore, since a load is thereby imposed on the entire Internet, the above described problem becomes even more critical and can not be ignored.
On the transmission side, for transmission of e-mail in volume, a fixed document format, called a template, is employed to generate e-mail data. And an application program is presently available that can automatically generate e-mail data for all of a number of intended recipients so long as the minimum information, such as a stock exchange or a stock price, is inserted into the template, and using this application, one of the currently available PCs (Personal Computers) can generate enough data for 1000 e-mails every second. That is, as an example, two hundred thousand e-mails can be created in about 200 seconds.
Furthermore, since a mail server on the reception side, particularly a mail server operated by a mobile phone company or a major ISP (Internet Service Provider), has a certain level of capability on the assumption that at least several hundred thousand to one million users might access, and also a mail server distributes e-mail only if it is accessed by a recipient, no big problem will occur, even with the current capability.
As is described above, for the transfer of a large volume of e-mail, data transfer among mail servers by SMTP has constituted a bottleneck.
To resolve this problem, as is shown in FIG. 2, an modified SMTP has been proposed according to which multiple e-mails are transferred collectively within one session. Specifically, in the “acknowledge sender address” process of FIG. 2, according to SMTP, a keyword “SLIDE” is transferred by the reception side to the transmission side to notify the transmission side that the reception side can cope with the expansion function. Then, the transmission side sequentially transmits, to the reception side, “recipient mailing addresses (A, B, . . . )” for respective recipients of multiple e-mails that are to be collated and transferred. At this time, “SLIDERANGE=**−**” data is also transmitted for the e-mail address of each recipient to represent the data portion (by using the locations of bytes) for mail text to be transferred to the recipient. As is described above, in accordance with this proposal, data for multiple e-mails are transmitted collectively in mass in order to reduce the procedures performed in accordance with SMTP.
However, so long as SMTP is employed, the protocol in itself requires that multiple servers be used to relay the e-mail data, and as a result, dramatic effects can not always be obtained. Further, in many cases where companies provide information for their clients by e-mails, the same mail text or almost all the mail text is employed for all the e-mails while only destination mailing addresses differ. In these cases, the amount of data for the mail text is enormously expanded when a large number of e-mails are to be transmitted, it can be said that no ameliorative effects are obtained.
Recently, banks and stock brokerages have been requesting the performance of the information distribution services using e-mail many times a day, so that they can promptly provide clients topical information, such as stock exchange and stock price information. And for the above described reasons, the current technique cannot cope with this request. To resolve the conventional technical shortcomings, it is one object of the present invention to provide a mail transmission system, a mail server, a mail transfer system and a mail transfer method so that a large volume of e-mail can be transferred rapidly.